Back in 2007, Donald Trump sent the newly sworn-in speaker of the House, Nancy Pelosi, a letter celebrating her ascension.

“Nancy—you’re the best. Congrats. Donald,” the entertainer wrote, Politico reported in 2011. The correspondence between the two has taken a more combative tone recently, which makes the current moment all the stranger: Pelosi might be the biggest barrier between President Trump and an impeachment inquiry right now.

Pelosi has made her personal opposition to impeaching Trump clear. In March, for example, she told The Washington Post, “I’m not for impeachment … Impeachment is so divisive to the country that unless there’s something so compelling and overwhelming and bipartisan, I don’t think we should go down that path, because it divides the country. And he’s just not worth it.”

Until recently, most members of the Democratic caucus have been willing to go along with their leadership’s position. (A few backbenchers have consistently called for impeachment.) But the past few days have brought signs that that’s no longer true.

Democratic members are growing more frustrated with the Trump administration’s strategy of stonewalling House investigations. The latest move came late Monday, when the White House said it was “directing” former White House Counsel Don McGahn not to appear for testimony to the House Judiciary Committee. McGahn duly did not appear Tuesday. As I noted, McGahn’s testimony would probably come closer to a preview of an impeachment inquiry than any other witness’s appearance.

During a meeting on Monday, according to reports in Politicoand the Post, several Democrats told the speaker that it was time to launch an impeachment inquiry, including Representatives David Cicilline of Rhode Island, Jamie Raskin of Maryland, and Joe Neguse of Colorado. What’s interesting about these members is they’re all members of the Democratic leadership team. Today’s leadership teams are large, and none of these representatives is majority leader or whip, but they’re also not backbenchers.

I think that overwhelming evidence has been presented to us in the Mueller report, and outside of it too, of high crimes and misdemeanors, and we should launch an impeachment inquiry. Remember, an inquiry doesn’t prejudge the outcome. We’re not talking about articles of impeachment.

As a member of the Judiciary and Oversight committees, I do think the logic of an impeachment inquiry is pretty overwhelming at this point.

While some of these members have been on the vanguard of calling for tough action against the administration—Raskin told my colleague Russell Berman earlier this month that the House should consider arresting officials whom it holds in contempt—the open impeachment talk is a shift. This isn’t to say that in an un-whipped vote of House Democrats impeachment would win. Until it’s actually taken, that’s difficult to determine.

The pro-impeachment Democrats have their own strange ally: Representative Justin Amash, a Republican from Michigan. Over the weekend, he announced that he supported impeachment. His argument was unusual in its specificity, and he pointedly said that few of his colleagues had actually read Special Counsel Robert Mueller’s report. In fact, Amash went further than most Democrats. Even Raskin is quick to note that opening an inquiry doesn’t automatically lead to impeachment, while Amash stated flatly that Trump has committed impeachable offenses. Because Amash is a Republican, his position also means that there’s now bipartisan support for impeachment, at least in name.

Pelosi is unmoved. She and her closest allies reportedly pushed back on the restive members of the caucus during Monday’s meeting. From her perspective, none of the underlying reasons for going slow have changed. Amash may create nominal bipartisanship, but the fierce backlash he generated—Amash drew a primary challenger and was chastised not only by the president but by the House Freedom Caucus, the closest thing to his clique in Congress—shows that at least for now, his announcement is more symbolic then seismic.

Moreover, the speaker believes that Democrats are winning on their present course. On Tuesday, a federal judge incredulously rejected the Trump administration’s attempt to block the president’s accounting firm from turning over his financial records. In April, another federal judge said that a suit from House Dems alleging that Trump violated the Constitution’s emoluments clause could go forward. The White House has placed its hope on courts blocking Democrats, and so far the strategy isn’t working. Why hastily change course and embark on a risky impeachment inquiry now, when things are all breaking Democrats’ way? Impeachment will still be an option later.

This seems to be the subtext for many of Pelosi’s comments on impeachment. On face, she says she’s not in favor. But her explanations and reasons suggest a different answer: Maybe, just not yet. Both factions of Democrats insist they’re acting not out of political expedience, but principle. “This is not about politics, it’s about what’s best for the American people,” Pelosi said Monday, according to Politico. The pro-impeachers agree: Even if there aren’t more Republicans with them, and even if conviction in the Senate is sure to fail, it’s the right thing to do.

Those high-minded explanations aside, it’s also unknowable what the most politically advantageous course of action is for Democrats. The White House doesn’t know either. Trump has seethed at the idea of being impeached, but his stonewalling strategy seems almost designed to force Democrats into impeaching him. For the time being, Nancy Pelosi might be the one thing restraining them.

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David A. Graham is a staff writer at The Atlantic, where he covers U.S. politics and global news.